WATCH ABOVE: Excessive steaming is being blamed for four big oil leaks near Cold Lake, Alberta. Permanent restrictions have now been placed on CNRL to prevent further contamination, but it has environmental groups calling for a hold on the practice. Carolyn Kury de Castillo reports.

What is this?

The Alberta Energy Regulator says excessive steaming was one of the reasons behind high-profile leaks at Canadian Natural Resources Ltd.’s Primrose oilsands project nearly three years ago.

The watchdog’s final report on the incident cites the ability of the bitumen-water mixture to make its way to the surface through old well bores and natural and man-made fractures in the rock.

CNRL had been using an extraction technique at the eastern Alberta project called high-pressure cyclic steam stimulation, the safety of which has been questioned by environmental groups.

AER executive vice-president Kirk Bailey says the technology has a good track record elsewhere in the province and there are currently no concerns about its use by other operators.

The AER says CNRL didn’t break any rules with its steaming technique, but the regulator has ordered the company to permanently reduce it’s steaming volumes at the site to make sure a similar incident doesn’t happen again.

The pressure restrictions may affect the pace at which CNRL is able to produce bitumen at Primrose.

Canadian Natural Resources, Ltd. provides media access to spills at its Primrose site near the Cold Lake Air Weapons Range in northeast Alberta. August 8, 2013.